I can't connect to the Internet!

When I sign in to my Xfinity account on my MacBook Pro, the WiFi icon on the top of my screen indicates that I'm connected. But I can't access any websites.

 

There are five white lights on the front of my modem. The top light - Power - shines steadily. The middle light - "Online" - does nothing. The other lights flash on and off.

 

I found the following under Network Preferences:

 

Network Preferences > 802.1X
Name: WiFi
Authentication: TTSL
Wireless Network: XFINITY
Security Type: WPA/WPA2 Enterprise
Trusted Certificate:
Trusted Servers: *.aaa.wifi.comcast.com,

 

If I remember correctly, the first time I tried to connect all the lights shone steadily except for Online, but I could be mistaken.

 

Another problem - Xfinity advertised two months of free service due to the coronavirus pandemic. So I signed up and had an Internet connection. But after setting up my modem, I've apparently lost my free connection, which means I can't connect to the Internet, period.

 

I've given up on customer support. I decided to try the forum, after which I'm cancelling my account.

 

Thanks for any tips.